In any event, I have a 55 tweed pro with a JBL that sounds great. Sometimes I swap it with for a vintage P15N when I want a more period sound, a bit grittier and not as loud. The vintage Jensens can be had for not too much money - not as big a demand for them as the 12"s

Thanks fellas. Great to get some feedback from such knowledgeable guys.

Which JBL are you using spike?

Not sure the owner wants to sound like Cliff Gallup Billy TBH, but I think he might be veering towards a JBL D130 based on recommendations from others and on-line demos.

Regarding field coil replacement, as I understand it there are two types - those where the field coil functions as a choke in the power supply and those that tap off the B+ and are terminated to ground.

The former typically has a resistance in the low 100s and can be replaced with a choke or a high wattage resistor as Billy says. The latter typically ohms out at 5K - 8K and besides energising the speaker, serves as a drain resistor that rapidly discharges the amp after power down.

The 5A5 circuit I'm dealing with has the second type of field coil and I'm measuring 6.8K across it. So it's far simpler to convert this amp to run a permanent magnet speaker.

I have a D130. Originals are a bit overpriced these days imo, but the Weber California gets pretty close to my ears. They are both quite heavy compared to the Jensen though - something to think about in a big box amp like a Pro.

TBH the Pro is so much heavier than my 5A3 Deluxe with a Celestion Blue that I'm wondering if the field coil Jensen is heavier than a regular Jensen P15 anyway. In which case, there might not be that much difference with a JBL.

Warehouse Guitar Speakers also has ceramic and alnico 15's in their "American vintage" line. I've got the G15C in a brownface vibrolux clone I put together a couple years back. Sounds good to my ears, and pairs well with the amp.

FTR...a D130 has an eleven pound magnet, and a 4 1/2" edgewound aluminum voice coil. I think the D130F's had edgewound copper gapped a tiny bit looser. JBL's are in a category all by themselves...they don't relate to regular speakers. They're wonderful though.
Jensen 15's have that tubby sound that harp players love.

Funny...I had a D130 in a 5E3 clone...everybody talks about squeaky clean and hi-fi, but mine definitely leaned toward tubby, like Billy says.
I wanted it so badly, then couldn't bond with it.
I've got a '54 5D5 Pro that sounds heavenly...I'll check which Jensen is in it tomorrow...P15Q, I think...

I've tried so many 15" speakers. Every one cited here is tasty in its own way. Hard to predict which one will sound good in a given amp. I tried several in my Victoria tweed pro (35115). Including a JBL D130, Weber 15A150, Weber Cali paper cap, another with aluminum cap, Big Ben, CTS ceramic from the 60s, a WGS ceramic. The winner in that amp was the Emi Legend 151 ceramic. That speaker has also been the winner in several other 1x15s, including the Lil Dawg DLX I'm playing now.

Your mileage may vary of course. For my tastes, the Legend 151 has turned into a pretty safe bet.

If a D130 isn't the best thing you've ever heard, it has a bad cone kit in it.

– Billy Zoom

Very possible...I was shocked at how it didn't deliver the goods, but even some of these Holy Grail items are subject to personal taste.
It also had a model designation I couldn't find anything out about.
I think it was a D130AS.

I went on a 15” quest. I still have a d130f , a d140, a Weber C12N copy, a celestion g15m and a 15” from out of the fender excelsior. They are all great speakers. The Weber was new though so i dont think it is broken in. I wouldn’t hesitate to recommend the excelsior speaker though. They turn up on eBay for under $50 . They are very light and sound great. I currently have it in my bassman clone . The d130 is in its own cab. The mounting bolts i had with the clone were not long enough to mount the jbl in that cabinet. The surrounds are thick on the jbl but they are outstanding speakers